An image of the upstream face of Hoover Dam. The name was officially changed from Boulder Dam to Hoover Dam in 1947.

An image of the upstream face of Hoover Dam. The name was officially changed from Boulder Dam to Hoover Dam in 1947.

An image of the upstream face of Hoover Dam. The name was officially changed from Boulder Dam to Hoover Dam in 1947.

An image of the upstream face of Hoover Dam. The name was officially changed from Boulder Dam to Hoover Dam in 1947.

A painted photo depicting Lake Mead and Hoover (Boulder) Dam. Text on front of post card: "Lake Mead in Black Canyon, Boulder Dam", "Boulder Canyon Project of the Business of Reclamation"; Text on back of post card: "Lake Mead is quite narrow, just above Boulder Dam, yet more than 500 feet deep, where it is confined between the somber cliffs of Black Canyon gorge. Beyond the gorge the waters spread extensively over the desert valleys to form a vast lake 115 miles in length, with a shoreline of more than 550 miles - the largest man-made lake in the world. Comfortable cruisers make regular scheduled excursions on Lake Mead."

Illustration of a night view of Boulder Dam, now known as Hoover Dam. Caption reads: "Boulder Dam at night, Colorado River." "U.S. Bureau of Reclamation photo" is typed in the top left corner.

An image of the upstream face and intake towers of Hoover Dam. The name was officially changed from Boulder Dam to Hoover Dam in 1947.